Return coupled electron discharge device circuit



Dec. 31, 1940. E. RAHN EIAL 2,226,740

RETURN COUPLED ELECTRON DISCHARGE DEVICE CIRCUIT Filed April 19, 1940 INVENTORS ERNST RAH/V AND BY IfRW/A/ W/LLWACHER ATTORNEY.

Patented Dec. 31, 1940 PATENT OFFECE RETURN COUPLED ELECTRON DISCHARGE DEVICE CIRCUIT Ernst Rahn and Erwin Willwacher, Berlin, Germany, assignors to Telefunken Gesellschaft fiir Drahtlose Telegraphie m. b. 11., Berlin, Germany, a corporation of Germany Application April 19, 1940, Serial No. 330,459 In Germany November 18, 1938 Claims.

The invention relates to a return coupled tube circuit which can be employed for the production or for the amplification and frequency multiplication of ultra short waves. In the customary 5 feed back circuit for decimeter waves exemplified in Fig. 1, a potential is derived from the inductance L or" the oscillatory circuit and the said potential is applied across the variable cathode impedance Rk to the grid-cathode path. For

optimum feed back a definite position of the sliding contact S is required. When changing the wave by varying the inductance L or the capacitance Ck, the feed back will be greatly displaced automatically so that the contact requires a subsequent resetting.

In accordance with the invention, this separate subsequent setting of the feed back at wave change is avoided in that the vacuum tube electrodes are provided at the same time on the one hand with separate circuits for the feed back and for the tuning and consumer coupling on the other hand.

A better understanding of the invention may be had by referring to the following description in conjunction with a drawing wherein Fig. 1 illustrates a known type of circuit; and Figs. 2, 2a and 3 illustrate different embodiments of the invention given by way of example only. Fig. 2 (I shows a return coupled vacuum tube R having connected across its grid and plate a bend or loop L1 and a second bend of loop L2, of which the first one serves solely for the setting of the feed back by means of the rotatable lever H and the latter serves simply for deriving output energy and for the tuning. The variation of the tuning takes places either by means of a condenser Ck, in a manner similar to Fig. 1, or by means of a short circuit bridge or bar bridging the bend, or in accordance with Fig. 20. by means of a rotatable lever H1. In place of this measure the wave may also be varied in that in the arrangement of Fig. 2 the bends L1, L2 are rotated against each other as a result of which the mutual inductance thereof varies.

In the form of construction shown in Fig. 2,

the tube is provided with simple electrode through leads only. If twice the number of through leads are provided, the idea of the invention can be 59 practiced in a manner shown in Fig. 3, wherein the two circuit bends are decoupled from each other to a wide degree. In Fig. 3 again the bend L1 serves for the setting of the feed back while the bend L2 serves for varying the wave and for 5 deriving the output energy. Bend L2 is provided with a short circuiting strap or bridge B for varying the tuning. Instead of arranging the two bends so that they are decoupled, the latter may also be coupled in a manner similar to Fig. 2.

In the form of construction shown in Fig. 3, the desirable advantage exists that the resonance resistance of the entire structure increases without causing the individual glass through lead have a lower loss resistance. This is due to the fact that in the two bends L1 and L2 only half the 10 wattless current flows at all times so that the power loss for each circuit is reduced to one fourth. The resonance resistance is a maximum if the bends L1 and L2 are of the same size.

What is claimed is: 15

1. An electron discharge device circuit for use with ultra short waves, comprising a grid, an anode, and a cathode located within an envelope,

a pair of closed circuits each connected between said anode and grid, means in: circuit with one 20 of said closed circuits for tuning the same to a desired frequency, and a connection from a point intermediate the ends of the other closed circuit to said cathode for insuring the operation of said device, said connection being adjustable over 20 said last closed circuit.

2. An electron discharge device circuit for use with ultra short waves, comprising a grid, an anode and a cathode located within an envelope,

a pair of closed circuits each directly connected between said anode and grid, means in circuit with one of said closed circuits for tuning the same to a desired frequency, and a connection from said cathode to a point intermediate the ends of said other closed circuit and movable thereover.

3. A return coupled oscillation generating system comprising a multi-electrode vacuum tube having a pair of circuits in parallel relation to a pair of electrodes of said tube, one of said circuits having means for changing the electrical constants thereof for afiecting the frequency of oscillation but not the degree of feed back, a connection from the other of said circuits to a third electrode of said tube, said connection being adjustable over said last circuit for affecting the degree of feed back but not substantially the frequency of oscillation.

4. An electron discharge device circuit having an anode, a cathode and a grid within an envelope, a pair of closed circuits each connected between said anode and grid and extending externally of said envelope from different portions thereof, whereby said closed circuits are uncoupled from an electromagnetic standpoint, means in circuit with one of said closed circuits for tuning the same to a desired frequency, a load coupled to said one circuit, and a connection from the other closed circuit to said cathode, said last connection being adjustable over a. portion of said last circuit.

5. A return coupled oscination generator comprising a vacuum tube having a cathode, an anode and a grid, a pair of closed circuits each connected between said anode and grid, one of said 'the other closed circuit.

circuits being the frequency determining circuit, a connection from the other closed circuit to said cathode, said connection including a variable cathode impedance and being slidably adjustable over said last closed circuit, said frequency determining circuit having means for controlling the frequency of oscillation substantially independ ently of the degree of feed back obtained from ERNST RAHN. ERWIN WILLWACHER. 

